Device for protecting the ear drum



a 18, 1943;, J. J. CANTOR 2,441,866

DEVICE FOR PROTECTING THE EAR DRUM Filed June 4, 1945 2 Sheets-Shet 1die-o6 r7. (FAA/r02,

' INVENTOR.

ATTORN EY.

y 1948- J. J. CANTOR DEVICE FOR PROTECTING THE EAR DRUM Filed June 4,1943 2 Sheets-Sheet 2 rifle-o5 z-Z' CA -roe,

INVENTOR.

ATTORN E Y.

seal with the wall of theauditor g canal,

Patented May 18, 1 948 EAIENT Price 2,441,866: Davina ma num-me HEsennnivi Jaceb JGafitur L105- Angeles, Calif. mations-Tune a iaiaseriaiNo, 489,596

'1 claim; (01. 128-152) I very: painful, due to the entrapment and com-It is another ob ect at this inventionito nrovide an ear plug whichfunctions in an; t mh iovedmanner to exclude water-from: the ears,v,and; hence Whichcanbeused as; an: effective ear stpphle for-- swimmers.

To satisfactorily f-lulfill ei'ther of these obfects, it is necessarythat the earglng bein intimate contact with the wall of the auditorycanal to, form a tight seal. One difficulty, in prlepar," satisfactoryear plusv isvthe faotthat the uditory canal is not a straight. round tlbesbi t f generalv an- 8 pattern directed med lwa d, T us, e m i part ahei analj m@l d forwardly andslightl y. upwards; the intermediate partis directed backwardl'xandztheinternal; part (the longest) slope forwarl and slightlv; downward. Besides these: bend'si the surface;- heexternalv Q t n/E o the canal; where aplug; must be placed isi uneven;due to the nroti bere ances marking the position of the: underlying;cartilagcnous and bony structnre of; the rexteins aIidiiLrmY meatusOther factors interf ering withmaintaining an ear plug propersealing;con; tact with the Wallsot the eanal i s the tendell-qyofthe tragus toexert ressure nosteriorlyfon part of the: plug projecting o twa zdlyinto; the; area of the cavium conchae, Also; the r-act that the earcanal changessits form andsizewith the movement of the mandible; 7

It is thus anotherolo' eot of; this" invention: to; p vi n ear p s i hisaneh e Q QQQQmmodatingi itself to the turns and bends of; the canalasWell as -to the projec'tipr s v on the canal l, d; furt er the movem n sf; the wall.

is i l n ther ob ct: f; this nvent n t p o e n ea u w ph: ma en er tWitt-re tial r ofgthe an l w er i i u t et te eg eeenuhi t dwith earplugs f the rpeii tendeh to; akeatisht i 3 the faot that the normal;auditor can is closed in an air tight manner at itsv er y th 1 tympanic,membran or ear dri rn which is ex! tremely sensitive to changes inpressure. the introduction of an object into the canal which fits thecanal in an air tight-manner is pr bh of air'betvveen; the ear drum andtheobject' soinserted. It isacoordingly another object of this inventionto providean ear plug arranged to prevent entrapment of air between; theplug and} ear drum during insertion o f-the plug.

It is stillanotherobjectof; this invention to provide an ear plug whichis soft and flexible, to guard against possible injury to-t'he'lini'ngofthe auditory canal or other parts, and; which has improveds'ound,absorbing properties.

It is still another object of'thi's invention; to provide in onemodification thereof, an ear plug inwhi'c'hva blast of air resultingfroma concu ssipn, explosion or the like, acts to improve theseal'between the plug and theauditory canal-i It is still anotherobjectof' this invention to provide in another modification thereof; anear plug which Will permit; equalization of; the air pressure on bothsides ofthe ear drum, after the plug i s in place:

It; is still another object of; this invention to provide aninlprovedsound-t absorbing material.

It is a still. f ur-ther object of this invention to provide asound'absorbing material which is resilient.

It is a still further object of this inventionto provide a sound;absorbing material formed of cq nmin ited"material-and including meansto prevent such material; from packing or forming masse invention,possesses many other advanrages and has other objects which may be mademer ea i peren 'from e ohsid o va e bod men s h nv n n-- r his,

purhnsefthe e ar sh wn a numb ro ff rms in intentio s est d d y t e pend dl m- Be ht em heawin s 7 Fi res is a: su tant a ly v rt ca sctionthrough the auditory canal, showing an ear plug.

Figure 5 is a longitudinal section through a plug incorporating one formof the invention;

Figure 6 is a cross section taken on line 6--6 of Figure 5;

Figure 7 is a view similar to Figure 5 but showing the device as it maybe collapsed for placement in the ear;

Figure 8 is a front elevation of the device of Figure '7;

Figures 9 and 10 are views similar to Figure 5 but showing modifiedforms of the invention;

Figure 11 is an elevation of the device of Figure 10, taken from theleft;

Figure 12 is a view of a fragment of the improved sound absorbingmaterial, greatly magnilied; and

4 plug I2 and the wall of the canal I0 is thus provided so that no airis compressed between the plug I2 and the ear drum II as the plug isinserted. After insertion in the ear, the outer end of the tube I5 isreleased allowing air to enter the tube l5, so that the wall I! expands,due to its resilience, into intimate contact with the inner surface ofthe canal II]. It will be readily understood that in this condition,plug I2 efiectively seals and closes the canal I0. Obviously, the plugI2 may be used to prevent entry of water into the ears, as for example,of a diver or swimmer.

It will be apparent that when the plug I2 is in the tube [5 toward oraway from the ear drum Figure 13 is a View partly in section showing afurther modified form of the invention.

Referring to Figures 1 and 2 of the drawings, a portion of a human headadjacent the ear is shown in section, the auditory canal indicated byI6, being closed at its inner end by the ear drum Ii. The outer end ofthe canal I6 is closed by a plug or closure I2 incorporating theinvention. As shown in these figures, the canal I0 follows a reverselycurved path and is of varying cross section. Further, the Walls of thecanal are not smooth, but are rendered irregular by variousprotuberances as indicated by I3.

Referring to Figures 4 to 8, it will be seen that the plug I2 comprisesa generally cylindrical tube I6 closed at one end by a wall I6 which isout:- wardly convex to facilitate insertion of the plug in the ear andopen at its opposite end. It is to be understood that the plug is madeof soft resilient material such as rubber and that the portion I! of thewall of the tube I5 which enters the canal is relatively thin. Forexample, a rubber wall having a thickness of .024" has been found to besatisfactory. This enables the plug I2 to adapt itself to theirregularities of the inner surface of the canal I6 and the plug therebyestablishes a circumferential seal with the canal wall over asubstantial area along the length of the canal, as will appear from aninspection of Figures 1 and 2. Furthermore, this resilience enablestheplug to maintain such contact regardless of movements of the canal wallor changes in shape of the canal incident to movement of the jaws. Tolimit movement of the plug I2 into the canal Ill, an external projectionor flange I8 is provided on the tubelb intermediate its ends. To permitmore satisfactory placement of the ear plug in the canal as well as toprevent exertion of pressure on the external portion of the plug, theflange I8 need not be made to extend entirely about the periphery of thetube i5, but may be omitted over a part thereof, as indicated at It.This allows the plug I2 to freely pass the tragus indicated by 2| inFigures 2 and 3. When it is desired to insert the plug I2 in the ear,the plug may be flattened to about the form shown in Figures 7 and 8.This is accomplished by first pinching the closed end between the thumband forefinger of one hand, forcing most of the air out of the tube I5.The open end of the tube may be then closed in an air tight man- I I,will act upon the air confined between the plug and the ear drum, toproduce changes of pressure on the ear drum. It is necessary to preventsuch movement of the end wall I6, as otherwise the important purpose. ofthe plug will not be achieved. Thus, it is necessary particularly toprevent strong blasts of air, such as those caused by concussions, fromso moving wall I6 of the plug, as otherwise damage or injury to the eardrum may result. For this purpose the end wall I6, in one form of theinvention, is made stiffer than the tube wall IT. For example, if theplug I2 is made entirely of rubber, a satisfactory thickness forthe wall16 has been found to be about four times-the thickness of the wall I!(see Figure Further, the opposite end of the tube I5 has a large openingfor freely admitting air pressure from such blasts to the interior ofthe plug.

It is believed that due to the greater yieldability of the wall I! ascompared with that of end wall I6, increase of pressure within the plugI2 causes this wall to be expanded to more tightly engage the surface ofthe canal I0, thereby preventing such pressure from forcing the plu as aunit further into the canal, as well as preventing longitudinal or axialstretching of the wall I! by the pressure acting on the wall I6, so thatthe wall I6 is not displaced. Further, it is preferred that the open endof the tube I5 be entirely unobstructed so that no barrier is presentedupon which the blast mayact to force the plug bodily into the ear. Thestiffness of the wall I6 is such that this wall is not deformed by thepressure. Thus, since this end wall I6 is neither deformed nor displacedby momentary increase of air pressure, the ear drum is protected fromthe effects of concussions or'th like. Due to the large opening into theplug I2, the tendency for such blasts to pass between the wall of theplug and the wall of the canal is greatly reduced; also, theeffectiveness of the seal between these walls is improved bytheincreased pressure, as just described.

In the event that it is not necessary to guard against concussion,artillery fire and such, but it is only required to protect the earsagainst industrial noises such as that of riveters or machinery, thatform of the invention illustrated in Figures 9 to 11 may be used. InFigure 9, a plug 25 is shown including a thin walled tubularmember26 ofresilient material with a rounded integral end wall 21 and a limitingflange 28. However, in this form, the end wall 2'1 may be substantiallythe same thickness as the tube wall, while flange 28 may be thinner thanthe wall of tube 26. Thus, the flange 28 is suiflciently flexible toreadily pass the tr'agus and .can extend completely around the plug. Afilling of.

porous sound absorbent material 30 is placed c ances;

in the member '26, being retained therein by a porous plug 3! such as,of felt or other suitable material secured in the open end, of the tube26. ll-he material 39 is resilient to permit the tube 26 a; becompressed for insertion in the ear without impairing the soundabsorbent quality of the plug. This form of plug cannot be flattened forsuch insertion to as great a degree as was the first form described, butcan be readily compressed to reduce its cross section renderinginsertionin the auditory canal it easy and at the same time provide apassage to permit the air in the canal to escape as the plug isinserted.

In Figures and 11, a plug similar to that just described is provided andis filled with similar sound absorbent material 39. In this form of theinvention, the end wall 3? is perforated as indicated by 38. Since thefelt plug 3! is quite porous, air can thus pass through the plug 35 toand from the space in the canal I E]- between the plug 35 and theeardrum i I. Since the other side of the ear drum H is subjected toatmospheric pressure at all times through the nose and Eustachian tube,this plug permits equalization of pressure on opposite sides of the drumll. Thus, a person using the plug suflers no discomfort due to pressurechanges of the atmosphere in which he works.

Due to the small amount of sound absorbent material 36 which it ispossible to use in a plug, this material must be very effective for theplug to be of any use in guarding the ear against noise. Also, thismaterial must be resilient as previously pointed out, so that the filledplug can adjust itself to the projections and turns of the auditorycanal, and can be inserted in the manner set forth. Accordingly, a novelmaterial is provided which will now be described in detail.

As is well understood, sound has many of the l,

characteristics of light and energy, in that it can be reflected,refracted and absorbed. Sound has the quality of being able to move alonor through solids, and its velocity is decreased by passing through longnarrow passages. Further, sound exerts pressure, and hence its energycan be dissipated by causing it to contact suitable materials. Mostsound absorbent materials depend for their efiiciency upon the fact thatthey are perforated by numerous small holes. It has been found that thesound absorbent quality of a material depends on the size and length ofsuch holes.

In the instant case, an important ingredient of the sound absorbentmaterial or mixture :30 is a resilient material formed with innumerablepores or holesof minute size. Such a material may be for example airfoam rubber. Since discontinuity is an important feature in a trulysound absorbent material, this ingredient is ground or otherwise brokenup into very small particles. Each of these particles may be consideredas surrounded by a thin film of air, introducing another medium into thefield. Since sound, like light, may be reflected and refracted whenpassing from one medium to another, the passage of sound through thematerial involves a large number of reflections and refractions.

As is well known, when a sound wave strikes a medium of differentdensity from that in which it has been traveling, only a part of theenergy or pulse goes on into the new medium, and the remainder ispropagated backward through the first medium in the form of a reflectedwave in precisely the same way as that in which the original pulse was:propagated forward.

by utilizing amass of. sma1l... ncrous, ir egular particles surroundedand permeated by air, a material is provided whicnlacks homogeneity;this lack of homogeneity results in a dissipation of the energy of thesound waves by repeated reflections from materials. of differentdensity.

To further promote discontinuity and lack of homogeneity of the soundabsorbent material, short lengths of fibrous material are introducedinto the mixture. These cooperate to form mesh or irregular networks orwebs extending through the mixture in all directions and which furtherdissipate the sound energy. These fibers also assist in preventing themass from packing. Fibers of the bark of the redwood tree have beenfound satisfactory for such use, particularly since this material hassound absorbing characteristics of its own.

Since sound has the property of exerting force, any solid particle notin direct contact with another such particle will absorb some of thesound energy. Accordingly, it is desirable to add a finely divided heavysubstance to the mixture to increase its sound absorbent properties.Such additional material also increases the lack of homogeneity. Such asubstance to be suitable must not be toxic, and must not be resonant.Experiment has shown that salts of some of the heavy metals aresuitable, barium sulphate apparently having all the desiredcharacteristics. Accordingly, the particles of air foam rubber and thefibres are coated, at least partly, with barium sulphate. Thus, themultitudinous nets or webs are loaded with heavy material which furtherassists them in dispersing the sound energy.

Figure 12 is a copy of an enlarged photograph of a fragment of the soundabsorbent mixture 30. Therein, the particles of air foam rubber areindicated by 40, a few of the innumerable pores therein being marked 4!.Flecks of the metal salt are indicated by 42 and the fibrous material by43.

This mixture 3% is fed into the plug 25 or plug t5 by gravity, so thatany tendency to pack during filling is avoided. In this way theresilience of the material acts to maintain the plug in shape, at thesame time it is soft and flexible so as to be readily conformable to theshape and irregularities of the auditory canal, and has no resonantcharacteristics.

Figure 13 shows a modified form of device for utilizing the soundabsorbent mixture. Therein, a pair of ear mufis or caps 45 are disposedon the opposite sides of a wearers head and are arranged to cover theears. Each cap 45 has an inner wall 46 and outer wall 41 which cooperateto define a space $8 which is filled with the sound absorbing mixture39. Caps 45 are joined by a flexible band 49 which serves to retain themin place. These caps may include ear phones in the manner of telephoneand radio operators head sets, if desired.

I claim:

An ear stopper including a tubular portion adapted to be inserted in theear canal and having a thin resilient wall adapted to conform closely tothe surface of said canal; a wall across the inner end of said portion;aprojecting flange on said tubular portion spaced from the inner endthereof, to limit the insertion of said portion in said canal; a body ofresilient, sound absorbent material in said portion; which portion withcontained absorbent material retains its resilience and ability toconform closely to the ear canal;

and means forming an air passage through said stopper, communicatingwith the exterior thereof on opposite sides of the canal engagingportion to permit equalization of pressures inside and outside the ear,said means including a restricted opening through the end wall and apassage through said body of material.

7 JACOB J. CANTOR.

7 REFERENCES CITED The following references are of record in the file ofthis patent:

STATES PATENT Number Number 7 66,949

Name Date King July 29, 1884 Johns Nov. 25, 1890 Baum Feb. 4, 1941Knudsen June 24, 1941 FOREIGN PATENTS Country Date K Germany Feb. 4,1893 Netherlands July 30, 192i

